結果
| 問題 | No.1103 Directed Length Sum |
| ユーザー |
 Kazun
|
| 提出日時 | 2021-03-05 18:00:30 |
| 言語 | PyPy3 (7.3.15) |
| 結果 |
AC
|
| 実行時間 | 1,450 ms / 3,000 ms |
| コード長 | 10,463 bytes |
| コンパイル時間 | 216 ms |
| コンパイル使用メモリ | 82,268 KB |
| 実行使用メモリ | 336,884 KB |
| 最終ジャッジ日時 | 2024-10-06 19:03:22 |
| 合計ジャッジ時間 | 13,583 ms |
|
ジャッジサーバーID （参考情報） |
judge4 / judge5 |
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テストケース
テストケース表示| 入力 | 結果 | 実行時間 実行使用メモリ |
|---|---|---|
| testcase_00 | AC | 39 ms
55,812 KB |
| testcase_01 | AC | 42 ms
56,052 KB |
| testcase_02 | AC | 852 ms
336,884 KB |
| testcase_03 | AC | 569 ms
283,424 KB |
| testcase_04 | AC | 771 ms
181,096 KB |
| testcase_05 | AC | 1,450 ms
260,336 KB |
| testcase_06 | AC | 482 ms
145,644 KB |
| testcase_07 | AC | 140 ms
91,136 KB |
| testcase_08 | AC | 180 ms
98,532 KB |
| testcase_09 | AC | 114 ms
85,664 KB |
| testcase_10 | AC | 236 ms
110,240 KB |
| testcase_11 | AC | 824 ms
192,512 KB |
| testcase_12 | AC | 471 ms
146,188 KB |
| testcase_13 | AC | 239 ms
111,232 KB |
| testcase_14 | AC | 102 ms
83,616 KB |
| testcase_15 | AC | 350 ms
129,148 KB |
| testcase_16 | AC | 961 ms
204,716 KB |
| testcase_17 | AC | 991 ms
210,052 KB |
| testcase_18 | AC | 249 ms
110,188 KB |
| testcase_19 | AC | 891 ms
196,176 KB |
| testcase_20 | AC | 112 ms
83,848 KB |
| testcase_21 | AC | 167 ms
97,748 KB |
| testcase_22 | AC | 672 ms
172,852 KB |
| testcase_23 | AC | 389 ms
136,620 KB |
ソースコード
class Tree:
def __init__(self,N,index=0):
"""N頂点(index, index+1, ..., N-1+index)の根付き木を生成する.
"""
self.N=N
self.index=index
self.parent=[-1]*(N+index)
self.__mutable=True
def vertex_exist(self,x):
return self.index<=x<self.index+self.N
def __after_seal_check(self,*vertexes):
if self.__mutable:
return False
for v in vertexes:
if not self.vertex_exist(v):
return False
return True
def is_mutable(self):
return self.__mutable
#設定パート
def root_set(self,root):
"""頂点xを根に設定する.
"""
assert self.vertex_exist(root)
assert self.__mutable
self.root=root
def parent_set(self,x,y):
"""頂点xの親をyに設定する.
"""
assert self.vertex_exist(x)
assert self.vertex_exist(y)
assert self.__mutable
self.parent[x]=y
def child_set(self,x,y):
"""頂点xの子の一つにyを設定する.
"""
assert self.vertex_exist(x)
assert self.vertex_exist(y)
assert self.__mutable
self.parent[y]=x
def seal(self):
"""木の情報を確定させる.
"""
assert self.__mutable
assert hasattr(self,"root")
a=self.index
b=self.index+self.N
C=[[] for _ in range(b)]
p=self.parent
ve=self.vertex_exist
for i in range(a,b):
if i!=self.root:
assert ve(p[i])
C[p[i]].append(i)
self.__mutable=False
self.children=C
#データを求める.
def depth_search(self,Mode=True):
"""木の深さを求める.
"""
assert self.__after_seal_check()
if hasattr(self,"depth"):
return self.depth
from collections import deque
C=self.children
D=[-1]*(self.index+self.N)
E=[[] for _ in range(self.N)]
Q=deque([self.root])
D[self.root]=0
E[0]=[self.root]
while Q:
x=Q.popleft()
d=D[x]
for y in C[x]:
D[y]=d+1
E[d+1].append(y)
Q.append(y)
self.depth=D
self.tower=E
if Mode:
return D
def vertex_depth(self,x):
"""頂点xの深さを求める.
"""
assert self.__after_seal_check(x)
if not hasattr(self,"depth"):
self.depth_search(Mode=False)
return self.depth[x]
def __upper_list(self):
assert self.__after_seal_check()
if hasattr(self,"upper_list"):
return
if not hasattr(self,"depth"):
self.depth_search(False)
b=max(self.depth).bit_length()
X=[[-1]*(self.index+self.N) for _ in range(b)]
Y=X[0]
p=self.parent
rg=range(self.index,self.index+self.N)
for x in rg:
if x!=self.root:
Y[x]=p[x]
else:
Y[x]=self.root
for k in range(1,b):
Y=X[k-1]
Z=X[k]
for x in rg:
Z[x]=Y[Y[x]]
self.upper_list=X
def upper(self,x,k,over=True):
"""頂点xから見てk個親の頂点を求める.
over:(頂点xの深さ)<dのときにTrueならば根を返し, Falseならばエラーを吐く.
"""
assert self.__after_seal_check(x)
assert 0<=k
if not hasattr(self,"upper_list"):
self.__upper_list()
if self.vertex_depth(x)<k:
if over:
return self.root
else:
raise ValueError
i=0
while k:
if k&1:
x=self.upper_list[i][x]
k>>=1
i+=1
return x
def lowest_common_ancestor(self,x,y):
"""頂点x,yの最小共通先祖(x,yに共通する先祖で最も深いもの)を求める.
"""
assert self.__after_seal_check(x,y)
dd=self.vertex_depth(y)-self.vertex_depth(x)
if dd<0:
x,y=y,x
dd=-dd
y=self.upper(y,dd)
if x==self.root:
return x
if x==y:
return x
d=self.vertex_depth(x)
b=d.bit_length()
X=self.upper_list
for k in range(b-1,-1,-1):
px=X[k][x];py=X[k][y]
if px!=py:
x=px;y=py
return self.upper(x,1)
def __degree_count(self):
assert self.__after_seal_check()
if hasattr(self,"deg"):
return
self.deg=[0]*(self.index+self.N)
for v in range(self.index,self.index+self.N):
d=len(self.children[v])+1
if d!=self.root:
d-=1
self.deg[v]=d
return
def degree(self,v):
"""頂点vの次数を求める.
"""
assert self.__after_seal_check(v)
if not hasattr(self,"deg"):
self.__degree_count()
return self.deg[v]
def diameter(self):
"""木の直径を求める.
"""
assert self.__after_seal_check()
from collections import deque
def bfs(start):
X=[-1]*(self.index+self.N)
Q=deque([start])
X[start]=0
pa=self.parent
ch=self.children
while Q:
x=Q.popleft()
if X[pa[x]]==-1:
Q.append(pa[x])
X[pa[x]]=X[x]+1
for y in ch[x]:
if X[y]==-1:
Q.append(y)
X[y]=X[x]+1
y=max(range(self.index,self.index+self.N),key=lambda x:X[x])
return y,X[y]
y,_=bfs(self.root)
z,d=bfs(y)
return y,z,d
def path(self,u,v):
"""頂点u,v間のパスを求める.
"""
assert self.__after_seal_check(u,v)
w=self.lowest_common_ancestor(u,v)
pa=self.parent
X=[u]
while u!=w:
u=pa[u]
X.append(u)
Y=[v]
while v!=w:
v=pa[v]
Y.append(v)
return X+Y[-2::-1]
def is_brother(self,u,v):
"""2つの頂点u,vは兄弟 (親が同じ) か?
"""
assert self.__after_seal_check(u,v)
if u==self.root or v==self.root:
return False
return self.parent[u]==self.parent[v]
def is_ancestor(self,u,v):
"""頂点uは頂点vの先祖か?
"""
assert self.__after_seal_check(u,v)
dd=self.vertex_depth(v)-self.vertex_depth(u)
if dd<0:
return False
v=self.upper(v,dd)
return u==v
def is_descendant(self,u,v):
"""頂点uは頂点vの子孫か?
"""
assert self.__after_seal_check(u,v)
return self.is_ancestor(v,u)
def is_leaf(self,v):
"""頂点vは葉?
"""
return not bool(self.children[v])
def distance(self,u,v):
"""2頂点u,v間の距離を求める.
"""
assert self.__after_seal_check(u,v)
dep=self.vertex_depth
return dep(u)+dep(v)-2*dep(self.lowest_common_ancestor(u,v))
def __descendant_count(self):
assert self.__after_seal_check()
if hasattr(self,"des_count"):
return
if not hasattr(self,"tower"):
self.depth_search(False)
self.des_count=[1]*(self.index+self.N)
pa=self.parent
for T in self.tower[:0:-1]:
for x in T:
self.des_count[pa[x]]+=self.des_count[x]
return
def descendant_count(self,v):
"""頂点vの子孫の数を求める.
"""
assert self.__after_seal_check(v)
self.__descendant_count()
return self.des_count[v]
def subtree_size(self,v):
"""頂点vを根とした部分根付き木のサイズを求める.
"""
return self.descendant_count(v)
def preorder(self,v):
"""頂点vの行きがけ順を求める.
"""
assert self.__after_seal_check(v)
if hasattr(self,"preorder_number"):
self.preorder_number[v]
from collections import deque
Q=deque([self.root])
T=[-1]*(self.N+self.index)
p=1
while Q:
x=Q.popleft()
T[x]=p
p+=1
C=self.children[x]
for y in C:
Q.append(y)
self.preorder_number=T
return T[v]
def dfs_yielder(self):
"""DFSにおける頂点の出入りをyieldする.
(v,1): 頂点vに入る
(v,0): 頂点vを出る
"""
assert self.__after_seal_check()
#最初
yield (self.root,1)
v=self.root
ch=self.children
pa=self.parent
R=[-1]*self.index+[len(ch[x]) for x in range(self.index,self.index+self.N)]
S=[0]*(self.index+self.N)
while True:
if R[v]==S[v]: #もし,進めないならば
yield (v,0) #頂点vを出る
if v==self.root:
break
else:
v=pa[v]
else: #進める
w=v
v=ch[v][S[v]]
S[w]+=1
yield (v,1)
def top_down(self):
assert self.__after_seal_check()
if not hasattr(self,"tower"):
self.depth_search(False)
for E in self.tower:
for v in E:
yield v
def bottom_up(self):
assert self.__after_seal_check()
if not hasattr(self,"tower"):
self.depth_search(False)
for E in self.tower[::-1]:
for v in E:
yield v
#================================================
import sys
input=sys.stdin.readline
N=int(input())
T=Tree(N,1)
F=[1]*(N+1);F[0]=0
Mod=10**9+7
for _ in range(N-1):
a,b=map(int,input().split())
F[b]=0
T.child_set(a,b)
root=F.index(1)
T.root_set(root)
T.seal()
pa=T.parent
D=[0]*(N+1) #長さの総和
E=[0]*(N+1) #道の本数
for x in T.bottom_up():
if x==root:
continue
y=pa[x]
E[x]+=1 #自分から自分への道を加算
D[y]+=D[x]+E[x]
E[y]+=E[x]
D[y]%=Mod
E[y]%=Mod
print(sum(D)%Mod)